Initial tract formation in the brain of the chick embryo: selective expression of the BEN/SC1/DM-GRASP cell adhesion molecule.

摘要: This study reports the spatio-temporal pattern of BEN expression (a molecule immunoglobulin superfamily) during early stages first axonal tract formation, in fore- and midbrain chick embryos [Hamburger Hamilton (HH) 12-22]. The has been analysed using immunohistochemistry non-radioactive situ hybridization. Furthermore, double labelling experiments (combining anti-class III beta-tubulin, a pan-neuronal marker, anti-BEN antibodies) have carried out to determine whether is expressed by all tracts. neurons expressing appear around stage HH13-14, caudal diencephalon. They belong interstitial nucleus Cajal, their axons are components medial longitudinal fasciculus. By HH14, two other tracts appear: postoptic commissure descending root mesencephalic trigeminal nerve. Only latter expresses BEN. At later development numerous new telencephalic, diencephalic domains. few them (the fourth nerve, lemniscus lateralis, tectobulbar habenulopeduncular tracts) express In positive systems, cell bodies, growth cones uniformly labelled antibody. We found that none grows preferentially at interneuromeric boundaries. Moreover, each formed several thin fascicles rather than single one. transient disappears shortly before hatching. These results suggest may serve promote outgrowth precise neuronal systems involved 'axonal scaffolding'.